Developmental biology of the leech Helobdella

Weisblat, David A.; Kuo, Dian‐Han

doi:10.1387/ijdb.140132dw

Cited by 38 publications

(41 citation statements)

References 88 publications

(102 reference statements)

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“…The very first of these was carried out by Charles Otis Whitman, who examined development of the leech Clepsine (Whitman, 1878(Whitman, , 1887. Leeches, like other oligochaetes, exhibit a modified form of spiral cleavage involving the formation of germinal bandlets that generate most of the adult ectoderm, endoderm and mesoderm (see review by Weisblat and Shankland, 1985;Weisblat and Kuo, 2014 (Waldelt and Nagy, unpublished data). (C') Subsequently, the 3D macromere serves as the key organizer of development, in the same fashion described above for equal cleaving embryos.…”

Section: Cell Lineage Fate Mapsmentioning

confidence: 99%

“…The very first of these was carried out by Charles Otis Whitman, who examined development of the leech Clepsine (Whitman, 1878, 1887). Leeches, like other oligochaetes, exhibit a modified form of spiral cleavage involving the formation of germinal bandlets that generate most of the adult ectoderm, endoderm and mesoderm (see review by Weisblat and Shankland, 1985;Weisblat and Kuo, 2014 (Henry and Perry, 2008). On the basis of observations made in one species, Crepidula, there may also be an earlier signal that primes the animal micromeres that also involves the activation of MAPK in those cells (Henry and Perry, 2008)…”

Section: Cell Lineage Fate Mapsmentioning

confidence: 99%

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Spiralian model systems

Henry¹

2014

Int. J. Dev. Biol.

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The "Spiralia" represent one of the three major clades of bilaterian metazoans. Though members of this clade exhibit tremendous diversity in terms of their larval and adult body plans, many share a highly conserved early pattern of development involving a stereotypic cleavage program referred to as spiral cleavage. This group therefore represents an excellent one in which to undertake comparative studies to understand the origins of such diversity from a seemingly common ground plan. These organisms also present varied and diverse modes in terms of their ecology, development and life history strategies. A number of well established and emerging model systems have been developed to undertake studies at the molecular, genetic, cell and organismal levels. The Special Issue of the Int. J. Dev. Biol. entitled "Spiralian Model Systems" focuses on these organisms and here, I introduce this clade, pointing out different types of studies being undertaken with representative spiralian model systems. KEY WORDS: bilaterian metazoan, spiral cleavage, life history strategyThe Spiralia (Lophotrochozoa)Of the three major clades of bilaterians, the Spiralia (Lophotrochozoa) comprise nearly half of the extant metazoan phyla (see Fig. 1). Despite this fact, the group has received relatively little attention compared to the other two clades, the deuterostomes and ecdysozoans, notably in the areas of genetics, as well as molecular, cellular and developmental biology. This is due in part to the long standing predominance of key experimental models positioned within the Ecdysozoa, (e.g., the fruit fly Drosophila and the nematode, C. elegans), and the Deuterostomia, (e.g., chordates such as the Zebrafish and mouse, as well as a few invertebrate representatives from the Echinodermata).The Spiralia include 14 of roughly 36 metazoan phyla (Fig. 1). The Spiralia include the Lophotrochozoa, and sometimes these terms have been used synonomously. The clade "Lophotrochozoa" was first recognized by Halanych et al., (1995, see also Giribet et al., 2007 Helmkampf et al., 2008a,b;Dunn et al., 2008;Hejnol et al., 2009; Edgecomb et al., 2011) who showed that the Lophophorata (consisting of groups possessing characteristic ciliated feeding structures, such as brachiopods and phoronids), are clearly united with other protostome phyla that include annelids, molluscs, and nemerteans. The Spiralia, however, encompass an even larger group of metazoans, and the exact relationships amongst the Spiralia are, however, not fully resolved. The consensus from recent analyses suggest that there are two large sub-groups (clades). One group is the "Trochozoa," (Roule, 1891), which include Annelida, Int. J. Dev. Biol. 58: 389-401 (2014) doi: 10.1387/ijdb.140127jh Mollusca, Nemertea, as the "Eutrochozoa", together with the "Brachiozoa" (see Cavalier-Smith, 1998), comprised of Brachiopoda and Phoronida, and the "Polyzoa" (Funch and Kristensen 1995;Passamaneck and Halanych 2006; Helmkampf et al., 2008a,b;Edgecombe et al., 2011) consisting of the Bryozoa, E...

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Section: Cell Lineage Fate Mapsmentioning

confidence: 99%

Section: Cell Lineage Fate Mapsmentioning

confidence: 99%

Spiralian model systems

Henry¹

2014

Int. J. Dev. Biol.

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“…Teloplasm, a characteristic feature associated with unequal cleavage and D quadrant specification in clitellate annelids, consists of cytoplasm that is deficient in yolk but rich in messenger RNA (mRNA) and organelles (Weisblat et al 1984). Teloplasm is segregated to the D macromere at the second cleavage and thence to macromere D′ at third cleavage (stage 3, not shown) (Weisblat and Kuo 2014). At fourth cleavage, macromere D′ divides to form ectodermal and mesodermal precursors, proteloblasts DNOPQ and DM, respectively (stage 4b).…”

Section: Resultsmentioning

confidence: 99%

“…Embryos were obtained from a laboratory colony of the species H. austinensis (Kutschera et al 2013) as described elsewhere (Gline et al 2011; Weisblat and Kuo 2014). …”

Section: Methodsmentioning

confidence: 99%

Spatiotemporal expression of a twist homolog in the leech Helobdella austinensis

et al. 2017

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Genes of the twist family encode bHLH transcription factors known to be involved in the regulation and differentiation of early mesoderm. Here, we report our characterization of Hau-twist, a twist homolog from the leech Helobdella austinensis, a tractable lophotrochozoan representative. Hau-twist was expressed in segmental founder cells of the mesodermal lineage, in subsets of cells within the mesodermal lineage of the germinal plate, in circumferential muscle fibers of a provisional integument during segmentation and organogenesis stages and on the ventral side of the developing proboscis. Thus, consistent with other systems, our results suggest that twist gene of the leech Helobdella might function in mesoderm differentiation.

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“…In the lab, they can reach reproductive maturity after about a year, at which point they weigh around 10 g -a 400-fold increase that they gain from as little as six feedings. In general, the developmental biology of Hirudo has not been studied nearly as extensively as that of Helobdella robusta, which has been favored, among other reasons, because its embryos can be produced in large quantities and maintained much more conveniently in the lab (Weisblat and Kuo, 2014). Nevertheless, two very different recent studies of the development of Hirudo should not be omitted here.…”

Section: Development Of Nervous System and Behaviormentioning

confidence: 99%

A classic model animal in the 21st century: recent lessons from the leech nervous system

Wagenaar

2015

Journal of Experimental Biology

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The medicinal leech (genus Hirudo) is a classic model animal in systems neuroscience. The leech has been central to many integrative studies that establish how properties of neurons and their interconnections give rise to the functioning of the animal at the behavioral level. Leeches exhibit several discrete behaviors (such as crawling, swimming and feeding) that are each relatively simple. Importantly, these behaviors can all be studied -at least at a basal level -in the isolated nervous system. The leech nervous system is particularly amenable to such studies because of its distributed nature; sensory processing and generation of behavior occur to a large degree in iterated segmental ganglia that each contain only ∼400 neurons. Furthermore, the neurons are relatively large and are arranged with stereotyped topography on the surface of the ganglion, which greatly facilitates their identification and accessibility. This Commentary provides an overview of recent work on the leech nervous system, with particular focus on circuits that underlie leech behavior. Studies that combine the unique features of the leech with modern optical and genetic techniques are also discussed. Thus, this Commentary aims to explain the continued appeal of the leech as an experimental animal in the 21st century.

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Developmental biology of the leech Helobdella

Cited by 38 publications

References 88 publications

Spiralian model systems

Spiralian model systems

Spatiotemporal expression of a twist homolog in the leech Helobdella austinensis

A classic model animal in the 21st century: recent lessons from the leech nervous system

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